1. Field of the Invention
The present invention relates to video players and video playing methods for performing pause processing, such as temporarily interrupting playing of video.
2. Description of the Related Art
Generally, an interlaced video frame includes two fields, and pause processing for freezing video includes frame pause and field pause. Frame pause means freezing video using two fields, and high resolution can be realized. However, since one frame is composed of two fields, which are temporally shifted relative to each other, high-speed motion video causes video blurring. In contrast, field pause means freezing video using one field. Although field pause does not cause video blurring, video resolution is reduced since half the number of scanning lines used for one-frame video is used.
As described above, each of frame pause and field pause has advantages and disadvantages. Thus, it is preferable to adopt an optimal method based on video motion.
For example, digital versatile discs (DVDs) and digital broadcasting adopt an MPEG system as a method for recording video. In the MPEG system, video is encoded using three types of methods, such as discrete cosine transform (DCT), motion compensation, and entropy coding, in order to reduce the amount of data of video signals. Motion compensation is a method for representing data of the current field or frame and data of the subsequent field or frame using motion vectors and difference values of data. Motion compensation enables a significant reduction in the amount of data. (For example, see Japanese Unexamined Patent Application Publication No. 2000-188735 (PP. 4-11, FIGS. 1-4).)
Such motion vectors represent the intensity of video motion and enable determination of which type of pause processing, field pause or frame pause, is suitable.
Due to the use of motion vectors, as disclosed in Japanese Unexamined Patent Application Publication No. 2000-188735, the intensity of motion of video compressed by the MPEG system can be known. This method, however, requires a high processing load. For example, in a case where one field is composed of 720 ×240 pixels and a motion vector is defined by a 16×16 pixel macroblock, one field includes 675 motion vectors. For bi-directional prediction or field prediction, this number is increased by a factor of two or four. For example, in a case where the number of motion vectors is increased by a factor of four (that is, 675×4=2,700), some kind of calculation must be performed for more than 2,000 motion vectors at the moment of pause processing. Thus, the processing load is increased. Therefore, use of an expensive CPU with high processing power or an increase in the size of a circuit for parallel processing is needed.